Electron image data processing apparatus

ABSTRACT

Disclosed is an electron image correlation tube adapted to achieve correlation without mechanical or electrical nutation. This eliminates the need for considerable electronic equipment in system complexity. Fundamentally, the invention utilizes an electronic lens in combination with a sectioned anode cooperating with a differencing circuit to achieve the correlation. The outputs of the various sections of the sectioned anode are analyzed by the differencing circuit and the resultant signals are, through a deflection circuit, utilized to control the deflection yokes of the correlation tube and consequently accurately achieve the correlation.

United States Patent 1 Shoemaker 1 1 Aug. 7, 1973 l l ELECTRON IMAGEDATA PROCESSING APPARATUS John R. Shoemaker, Akron, Ohio [22] Filed:Aug. 10, 1971 [21] Appl. No.: 170,656-

Related U.S. Application Data [63] Continuation of Ser. No. 872,677,Aug. 10, 1971,

[75] Inventor:

abandoned.

[52] U.S. Cl. 315/11, 315/12, 315/31 [51] Int. Cl. H0lj 31/48 {58] Fieldof Search.....- ..3l5/10,1l,12, 31 R [56] 1 References Cited v UNITEDSTATES PATENTS 2,977,499 3/1961 Bockemuehl 315/10 X 3,054,019 9/1962'Hendry 3,278,780 10/1966 Carnahan et a1. 315/12 X Sm I2 PRESENT INPUTIMAGE 1 l l8 1 l REFERENCE IMAGE LECTION CIRCUIT 3,476.197 11/1969 Penixet al. 315/11 X 3,496,290 2/1970 Smith 315/11 X 3,555,346 l/l97l McGeeet al. 315/12 X Primary Examiner-Carl D. Quarforth Assistant Examiner-P.A. Nelson Att0rneyJ. G. Pere [57] ABSTRACT Disclosed is an electronimage correlation tube adapted to achieve correlation without mechanicalor electrical nutation. This eliminates the need for considerableelectronic equipment in system complexity. Fundamentally, the inventionutilizes an electronic lens in combination with a sectionedanodecooperating with a differencing circuit to achieve the correlation. Theoutputs of the various sections of the sectioned anode are analyzed bythe differencing circuit and the resultant signals are, through adeflection circuit, utilized to control the deflection yokes of thecorrelation tube and consequently accurately achieve the correlation.

TClairiisQiDriivihg Figures DIFFERENCING CIRCUIT Y ERROR SIGNALPATENIEDAUE 3.151.705

34 mxsi:

PRESENT INPUT 1 0 IMAGE l I w- T I l8 1 ERENCE GE DIFFERENCING CIRCUIT YERROR SIGNAL INVENTOR JOHN R. SHOEMAK ER MH'MW ATTORNEYS ELECTRON IMAGEDATA PROCESSING APPARATUS This application is a continuation of Pat.application Ser. No. 872,677, filed Aug..l0, 1,971 and now abandoned.

Heretofore it has been known'that there have been many and various typesof electronic correlation tubes which operate to correlate two images,either electronic or optical, or a combination of both. However,all'these prior art systems required some actual nutation between thetwo images in order to achieve the correlation. Normally a closed loopis utilized so that correlation is rapidly achieved and maintained. Theexpense for equipment and the complexity of operation is inherent wherenutation is necessary. Hence, a need to achieve nutationless correlationis present in the art. It is the general object of the present inventionto provide a nutationless correlation tube that operates on adifferentiation principle with reduced equipment cost and complexity.

The aforesaid object of the invention and other objects which willbecome apparent as the description proceeds areachieved in an apparatusto effect electron image data processing which comprises an electronimage tube, grid means to store image information as an electronicpattern in the tube, means to project image information as an electronpattern down the tube onto the grid, an anode means to collect theelectrons projected down the tube which pass through the grid which ischaracterized by an electrostatic lens positioned between the grid andthe anode means to direct all electrons moving parallel to the axis ofthe lens to impinge on the center of the anode, the anode divided intoat leasttwo separateregions surrounding a central region, means torepresent the number of electrons impinging onto the regions of theanode as the voltage, means to differentiate the voltage on therespective re gions and determine 1: and y error signals for thecorrelation of the stored electron pattern and the projected electronpattern, and means to deflect the projected electron pattern inaccordance with the x and y error signals to close the loop on thecorrelation between the two patterns.

For a better understandingof the invention reference should be had tothe accompanying drawings wherein FIG. 1 is a schematic system blockdiagram illustrating thebasic components in the new system;

FIG. 2 is an enlarged end view of the segmented anode; and

FIG. 3 is an enlarged broken away cross-sectional view of the storagegrid-illustrating the principle of the invention.

In many control operations it is desirable to maximize or minimize theintegral of a two dimensional function I (x a, y 3) over a'surface whichmay or may not be connected. Thisbasic problem may be attacked by eitherevaluating-the integral for many values of a and B and comparing thevalues this being equivalent to differentiating the functionwith respectto a and B, commonly called nutati'ng'. Also, the gradient of thefunction can be integrated over the surface. The integrating formpossesses the attraction of being conservative of time, but the"computation of vector integral taking account of the directionalna'tureof the derivative is cumbersome. An example of this type of computationis correlation guidance with a two level reference in which case it isdesired to maximize or minimize the integral over the white area of thereference. The normal procedure is to cause a and B to vary over somepath and control to minimum variation in the integral. This is classicalnutation.

The instant invention utilizes an electronic image correlation tube toevaluate directly andco'ntin'uously the derivative of the surfaceintegral without notation and without differentiation of the function.

It is the general purpose of this invention to p'rovde a means wherebyan electron image correlation tube can deliver separately andcontinuously an electrical signal proportional to each of the orthogonalline integrals of dx and dy within a predetermined surface. Theinvention presupposes the condition that prevails in an electron imagecorrelation tube upon whose storage mesh is stored reference black andwhite scene signals. It is generally understood by those skilled in theart that in the black areas of the storage mesh 10 of a tube 12 as seenin FIG. 1, when the tube is operated in a read-out mode, the grid wiresof the storage mesh 10 and a collector mesh 14 are at a referencepotential of 0 volts or greater. The potential at a photocathode 16 istypically a few volts and the insulation in this region is likewisecharged to this potential so that an electron entering at a position asseen in FIG. 3, is reduced to 0 velocity before arriving at the storagemesh 10 and returns to the collector 14. Hence, the electron flow is cutoff in this region.

Likewise in the white region,- the insulation at cathode 16 is at 0potential and hence an electron entering at point as seen in FIG. 3emerges with velocity unchanged. v

However, in the transition region corresponding to the contours aroundthe white regions an electron en. tering at pointv as seen in. FIG. 3,is bent towards the white region and emerges at an angle 6 depending onthe spacing of the meshes and the steepness of the transition. I havefound that if the electrons with left velocity vectors can be separatedfrom those traveling to the right and straight ahead and each of theseseparately collected, the following equationsresult:

I I dx i i;

I0 I n d The functions i, and i, are the collected currents with leftand right components and i and i, are those with upward and downwardcomponents. The requisite separationis achieved by placing aneectrostaticlens 20 behind the storage mesh 10 as it can be seen thatall the electrons with velocity vectors oriented in a common directionpass througha common point in the focal plane. The electrons movingparallel to the axis of lens 20 will pass through the focal point of thelens.

Hence, if such a lens 20 has its axis aligned with the axis 18 of thehousing 12, and the anode 22 is divided into-a least two separate"areas, although five are indicated in FIG. 2, the current collectedonsector as seen in-FIG. 2 will be proportionalto I IdS and (9 12 toeither maximize or minimize the surface integral according to the imageinput being either negative or positive. Typical deflection yokes thatcould be utilized are illustrated in U.S. Pat. Nos. 3,423,624;3,424,937;

3,430,092 and 3,476,197. A typical differencing circuit is described atpage 753 of The Encyclopedia of Electronics, edited by Charles Suskind,l962.

A differencing circuit which would readily achieve the objects of theinstant invention is shown in FIG. 18 in the text ElectronicFundamentals and Applications, Third Edition" by John D. Ryder, andpublished by Prentice-Hall in 1964. Of course, any of numerousdifferencing circuits are contemplated to achieve the objects of theinvention.

Hence, it is seen that the invention provides a tech nique using anelectron correlation tube with an electrostatic lens to evaluatedirectly and continuously the derivative of the surface integral withoutnutation. It provides an electrical signal proportional to theorthogonal line integrals which can be utilized through a deflectioncircuit to control the electronic image passing down the tuberepresenting either an input image or the reference image, dependingupon which image, is initially stored upon the storage grid 10, in amanner well understood by those skilled in the art..

The invention also contemplates that a metalized coating 40 is providedon the internal surface of the housing 12 to collect the electrons thatveer so much that they wont hit the collector anode 22 and might bounceback to give false readings. A colloidal suspension of graphites inwater such as Aqua Dag, as made by Acheson Colloids Company of PortHuron, Mich., would be suitable for this purpose.

While in accordance with the Patent Statutes, only the best knownembodiment of the invention has been illustrated and described indetail, it is to be particularly understood that the invention is notlimited thereto or thereby, but that the inventive scope is defined inthe appended claims.

What is claimed is:

1. Apparatus to effect electron image data processing which comprises:

an electron image tube, grid means for storing image information as anelectronic pattern in the tube, means for projecting image informationas an electronic pattern down the tube onto the grid means, and an anodeto collect the electrons projected down the tube which pass through thegrid, the anode being divided into at least two separate regionssurrounding a central region, I each region producing an outputelectrical signal indicative of the number of electrons impingingthereon, which is characterized by: an electrostatic lens positionedbetween the grid and the anode to direct all electrons having commonvelocity vectors upon reaching the electronic lens to correspondinglycommon regions on the anode;

means for determining the differences between the electrical signals ofthe respective anode regions surrounding the central region, thesedifferences being error signals for the correlation of the storedelectronic pattern with the projected electronic pattern; and

means for deflecting the projected electronic pattern in accordance withthe error signals so as to close the loop on the correlation between thetwo patterns. V

2. The apparatus as recited inv claim I wherein the means for projectinginformation as an electronic pattern comprises a photocathode and meansfor projecting optical image information onto the photocathode forconversion thereby into an electronic pattern.

3. The apparatus as recited in claim 1 which further includes aconductive layer on the internal surface of the tube for collectingstray electrons.

4. The apparatus as recited in claim 1 wherein the anode is separatedinto at least four separate and distinct regions surrounding a centralregion.

* 18 i I i

1. Apparatus to effect electron image data processing which comprises:an electron image tube, grid means for storing image information as anelectronic pattern in the tube, means for projecting image informationas an electronic pattern down the tube onto the grid means, and an anodeto collect the electrons projected down the tube which pass through thegrid, the anode being divided into at least two separate regionssurrounding a central region, each region producing an output electricalsignal indicative of the number of electrons impinging thereon, which ischaracterized by: an electrostatic lens positioned between the grid andthe anode to direct all electrons having common velocity vectors uponreaching the electronic lens to correspondingly common regions on theanode; means for determining the differences between the electricalsignals of the respective anode regions surrounding the central region,these differences being error signals for the correlation of the storedelectronic pattern with the projected electronic pattern; and means fordeflecting the projected electronic pattern in accordance with the errorsignals so as to close the loop on the correlation between the twopatterns.
 2. The apparatus as recited in claim 1 wherein the means forprojecting information as an electronic pattern comprises a photocathodeand means for projecting optical image information onto the photocathodefor conversion thereby into an elecTronic pattern.
 3. The apparatus asrecited in claim 1 which further includes a conductive layer on theinternal surface of the tube for collecting stray electrons.
 4. Theapparatus as recited in claim 1 wherein the anode is separated into atleast four separate and distinct regions surrounding a central region.